Method for on-site drug detection in illicit drug samples

ABSTRACT

The invention is intended for illicit drug detection, preferably to Cocaine detection in street samples containing in addition to Cocaine also adulterants and/or diluents (also denominated as cutting agents) used for increasing the quantity of the product and/or for disguising the existence of Cocaine. The invention provides preparing of the liquid street sample, taking an aliquot of said sample, its analysis with help of SFS (Spectral Fluorescence Signatures) technology, fixing the result of analysis as a reference value, the subsequent acidification of the liquid sample, taking an aliquot of the acidified liquid sample and its analysis with help of SFS technology, fixing the result of analysis and comparing said result with the reference value. The result of comparison enables to differentiate between Cocaine Base and Cocaine hydrochloride in the street sample.

FIELD OF THE INVENTION

This invention relates to the field of illicit drug detection,preferably to Cocaine detection in street samples. In the sense of thepresent invention, a street sample is a product containing in additionto Cocaine also adulterants and/or diluents (also denominated as cuttingagents) used for increasing the quantity of the product and/or fordisguising the existence of Cocaine. More particularly the inventionrelates to a method based on fluorescence in solution and specificallyon the Spectral Fluorescence Signatures (SFS) technology, enabling toincrease sensitivity of Cocaine detection in the illicit drug samplesand allowing differentiation between Cocaine hydrochloride and Cocainebase.

BACKGROUND OF THE INVENTION

A system and a method for on-site drug detection and quantificationbased on the Spectral Fluorescence Signatures (SFS) technology aredisclosed in WO2005111586. The system of this invention consists of anultraviolet-visible light source, a condenser/filter assembly withfilter drive, an excitation monochromator with diffraction gratingdrive, a reference photo-detector, a cell assembly for liquid, solid andpowder samples, an absorption photo-detector, an emission monochromatorwith diffraction grating drive, and an emission photo-detector. Amicrocontroller unit is provided for device controlling, dataprocessing, and communication with an external computer via differentlink types. The detection and quantification of illicit drugs in theanalyzed sample are provided by measuring simultaneously the emissionspectra of fluorescence at every step of excitation wavelength inselected and fixed excitation, emission and absorption spectral windowsin a way to cover specific excitation, emission fluorescence andabsorption spectral ranges of all major drugs, adulterants and diluents;and processing the united result in a computer system based oncombination of preliminary prepared spectral library and specializedsoftware consisting of identification, interaction verification andautomatic calibration modules.

A system and a method of analysis of street samples disclosed inWO2005111586 are limited in detection by the concentration of thesubstances of interest, in particular Cocaine, at that the specificpatterns in SFS structure caused by said substances are not recognizedby the expert system due to too low their concentration and interferinginfluence of adulterants and diluents. Additionally to that the citedinvention does not provide reliable means to differentiate betweenCocaine hydrochloride and Cocaine base due to the same shapes of SFScaused by both forms of cocaine in water.

The need for a technical solution, which increases the selectivity ofon-site analysis related to Cocaine detection in a mixture with cuttingagents (adulterants and diluents) and allows differentiation betweenCocaine hydrochloride and Cocaine base, is mandated by the legalrequirements in illicit drug distribution prevention. The currentsentencing structure for Cocaine offenses (United States SentencingCommission. Guidelines Manual. 2004) is the result of the Anti-DrugAbuse Act of 1986. It established mandatory minimum penalties forpersons convicted of trafficking in a variety of controlled substances.The 1986 Act pegged the mandatory minimums to specific quantities ofdrugs distributed. The quantities triggering the Act's mandatory minimumpenalties are differed for various drugs and in some cases for differentforms of the same drug. Cocaine base, commonly referred to as crackCocaine, has been treated differently than Cocaine hydrochloride,commonly referred to as powder Cocaine. The Act established what hascome to be known as a 100-to-1 quantity ratio between the two forms ofCocaine. It takes one hundred times as much of powder Cocaine to triggerthe same mandatory penalties as for a given amount of crack. Congressalso distinguished crack Cocaine from both powder Cocaine and othercontrolled substances in the Anti-Drug Abuse Act of 1988 by creating amandatory minimum penalty for simple possession of crack Cocaine. Thisis the only federal mandatory minimum for a first offense of simplepossession of a controlled substance. Under this law, possession of morethan five grams of crack Cocaine is punishable by a minimum of fiveyears in prison. Simple possession of any quantity of any othersubstance—including powder Cocaine—by first-time offenders is amisdemeanor offense punishable by no more than one year in prison.

The cited documents illustrate necessity to detect and differentiateCocaine hydrochloride and Cocaine base and to provide reliable andselective detection of two forms of Cocaine to fight effectively againstthis illegal drugs trafficking and abuse.

SUMMARY OF INVENTION

Resulting from the drawbacks of the known technical solution, the firstobjective of the present invention is to provide a method for on-sitedrug detection in illicit drug samples using SFS analysis enablingreliable differentiation of Cocaine hydrochloride and Cocaine base in asample.

Another objective of the present invention is to increase thesensitivity of SFS analysis for Cocaine base detection in the mixtureswith cutting agents.

For achieving the above objectives, the suggested method for on-sitedrug detection in illicit drug samples bases on the analysis performedby the Spectral Fluorescence Signatures (SFS) technology and providesexecuting of the following steps:

preparing an aliquot liquid sample of a street sample for analysis;

introducing the aliquot liquid sample into the measuring cell of an SFSdevice;

providing the first measurement of SFS of the aliquot liquid sample;

fixing the result of the first measurement of SFS of the aliquot liquidsample as a reference value;

preparing an acidified aliquot liquid sample after the firstmeasurement;

providing the measurement of SFS of the acidified aliquot liquid sampleafter passing the time limit necessary for dissolving of Cocaine base;

comparing the reference value and the result of the measurement of SFSof the acidified aliquot liquid sample, and

considering lack of any cocaine in the street sample proved if thereference value is zero and the result of the measurement of SFS of theacidified aliquot liquid sample is the same; or

considering the existence of Cocaine base in the street sample proved ifthe result of the measurement of SFS of the acidified aliquot liquidsample exceeds the reference value; or

considering lacking of Cocaine base and the existence of Cocainehydrochloride in the street sample proved if the result of themeasurement of SFS of the acidified aliquot liquid sample is below thereference value or equals to the reference value, and the referencevalue differs form zero.

The preferred time limit provided for dissolving of Cocaine base is atleast 3 minutes.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1: The flow chart of two-phase procedure of a sample analysis forCocaine hydrochloride and Cocaine base

FIG. 2: Increase of fluorescence intensity of Cocaine base in water (2mg/ml) in two-phase procedure.

FIG. 3: Increase of fluorescence intensity of Cocaine base in water (0.1mg/ml) in two-phase procedure.

FIG. 4: Increase of fluorescence intensity of Cocaine base (0.02 mg/ml)in two-phase procedure.

FIG. 5: Time dependency of fluorescence increase of Cocaine base (2mg/ml) after acidification.

FIG. 6: Time dependency of fluorescence increase of Cocaine base (0.1mg/ml) after acidification.

FIG. 7: Time dependency of fluorescence increase of Cocaine base (0.02mg/ml) after acidification.

FIG. 8: Fluorescence intensity of Cocaine hydrochloride (2 mg/ml) intwo-phase procedure.

FIG. 9: Fluorescence intensity of Cocaine hydrochloride (0.02 mg/ml) intwo-phase procedure.

DETAILED DESCRIPTION OF THE INVENTION

According to the present invention, the first step of the method ispreparing the liquid sample for analysis. For this purpose the drysample for analysis (sampled amount of powder or crushed pill) taken bysampling tool (e.g. spatula), is transferred into purified water, andwater with powder is mixed to assist dilution of the powder in water.After that, an aliquot (part) of prepared liquid sample is taken andintroduced into the measuring cell of the device according toWO2005111586 and SFS of the aliquot of liquid sample is measuredaccordingly. Upon acquisition of the SFS, the expert system of thedevice provides the detection of the substance of interest in thesample.

The second phase of analysis according to the present invention includesadditional treatment of remainder of the liquid sample, itsre-measurement with the same device and analysis with expert system(FIG. 1). The second phase is required and performed at followingconditions.

1. If no substance of interest, namely Cocaine has been reported by theexpert system upon completion of the first phase of analysis, suchresult can be due to two reasons:

-   -   a) there is no Cocaine in the sample at all;    -   b) there is Cocaine in the sample at such concentration that its        fluorescence is too low for detection or is influenced by        adulterants and diluents hampering the detection of Cocaine by        expert system;

Such uncertainty does not allow making the final conclusion about thestreet sample content.

2. If cocaine detection has been reported at the first phase ofanalysis, then differentiation between Cocaine base and Cocainehydrochloride is required.

To solve the problems remained after completing the first phase ofanalysis, the second phase of analysis procedure is performed (FIG. 1.)which is based on combined influence of two factors.

The first one is that the solubility of Cocaine hydrochloride in wateris much higher than the solubility of Cocaine base. Indeed, Cocainehydrochloride is quickly dissolved in water due to its high watersolubility (2-2.5 g/ml) but Cocaine base cannot be dissolved inconcentrations higher than 0.0017-0.0014 g/ml. (The Merck Index. 13thedition. 2001). Due to that a taken for analysis dry sample of Cocainebase cannot be dissolved completely in the conditions of the procedure:a part of insoluble Cocaine base remains in the tube at the firstmeasurement of the solute aliquot.

The second one is that addition of acid (preferably hydrochloric one) tothe liquid sample prepared for the first phase, promotes the reaction ofprotonation of Cocaine base, if it is present in the sample, convertingit to hydrochloric salt which is more soluble in the liquid sample(http://www.aapsj.org/view.asp?art=ps050104).

As a result of this reaction, more Cocaine becomes soluble, itsconcentration rises and fluorescence increases. This increase offluorescence changes the SFS at the second phase of measurement ofCocaine (FIG. 2-4), thus enhancing its easier detection with expertsystem. FIG. 5-7 show time dependency of protonation process for Cocainebase in acidified sample, indicating that minimal time delay betweenacidification and measurement by device is about 3 minutes.

Addition of acid to the sample containing Cocaine hydrochloride does notlead to the increase of the fluorescence intensity at the correspondingexcitation and emission wavelengths. The fluorescence intensity eitherdecreases or remains at the same level. (FIG. 8-9).

After completion of the first phase of analysis the intensity of Cocainefluorescence in the corresponding spectral pattern of SFS is fixed as areference value. The second phase analysis is performed by addition of1-2 drops of hydrochloric acid to the remainder of the liquid sampleprepared for the first phase of analysis, taking an aliquot of theacidified liquid sample and re-measuring of it is carried out in thedevice according to WO2005111586. In principle, it is possible also touse other acids instead of hydrochloric one for acidification of theliquid sample but the hydrochloric acid is preferable due to itscomparatively lower harmful properties and low volatile behavior.

After re-measurement the intensity of Cocaine detected at the secondphase of analysis—second phase intensity—is compared with the referencevalue.

If after completion of the second phase of analysis the expert systemstill does not detect Cocaine in acidified liquid sample, absence of anyCocaine in the street sample is treated as confirmed.

For the liquid sample containing Cocaine base, the second phaseintensity will be higher than the reference intensity due to increase ofCocaine concentration in the solute. In opposite, for the liquid samplescontaining Cocaine hydrochloride, the second phase intensity will belower than the reference intensity or remain the same (FIG. 8-9).Therefore the second phase of the procedure makes possible thedifferentiation between Cocaine hydrochloride and Cocaine base.

Table 1 shows the typical change of fluorescence intensity of Cocainebase in different percent concentration fixed by the applicant inexperimental laboratory samples.

TABLE 1 Fluorescence intensities, a.u. SFS ID Cocaine base First SecondIntensity number concentration, % phase phase difference, % 8187 1001470 7369 +401 8189 100 1344 7250 +439 8191 100 1172 7430 +439 8193 751161 7442 +541 8195 75 1239 7465 +503 8197 75 1152 7180 +523 8199 50 9997163 +617 8201 50 977 7139 +631 8203 50 982 6989 +612 8205 25 701 6250+792 8207 25 779 6376 +718 8209 25 726 6428 +785 8211 5 427 2528 +4928213 5 399 3035 +661 8215 5 462 3192 +591 8217 1 212 896 +323 8219 1 2621087 +315 8221 1 314 1842 +487

Table 2 shows typical change of fluorescence intensity of Cocainehydrochloride with cutting agents fixed by the applicant in experimentallaboratory samples.

TABLE 2 Cocaine First Second SFS ID hydrochloride phase phase Intensitynumber concentration, % intensity intensity difference, % 8223 100 77992781 −64 8225 100 7668 3130 −59 8227 100 7625 3390 −56 8229 50 7590 3608−52 8231 50 7738 3416 −56 8233 50 7796 3435 −56 8235 25 6617 3474 −488237 25 6671 3515 −47 8239 25 6667 3462 −48 8241 5 2748 1720 −37 8243 52661 1580 −41 8245 5 2546 1676 −34 8247 1 651 469 −28 8249 1 666 432 −358251 1 642 444 −31

The presented above data confirm efficacy of the procedure of sampleacidification for Cocaine hydrochloride and Cocaine base reliabledetection and their differentiation.

Two-phase analytical procedure provides differentiation between Cocainehydrochloride and Cocaine base. Significant increase of Cocaine basefluorescence and decrease of Cocaine hydrochloride fluorescence isobserved as a result of it. Time dependence of the studied acidificationeffect demonstrates that approximately 3 minutes is required to providethe changes and further stabilization of the fluorescence intensity.

Increase of fluorescence of Cocaine base after acidification providesalso higher sensitivity of the SFS analysis for this form of Cocaine.

A step-by-step performance of the present invention is presented below.

-   -   1. Transferring a proper amount of the street sample into a test        container with a rational volume of pure water.    -   2. Giving the amount of street sample to dissolve at possible        instant within 3 minute allowing any insoluble materials settle        to the bottom of the container.    -   3. Taking a proper aliquot of the dissolved street sample        (liquid sample) and placing it into the measuring cell of the        device according to WO2005111586.    -   4. Measuring the SFS of aliquot and detecting specific spectral        pattern of Cocaine. Measuring the intensity of Cocaine        fluorescence at the first phase of the two-phase procedure.    -   5. Acidification of the remainder of the dissolved street sample        with possibly non-soluble particles and giving a proper time for        non-soluble particles to dissolve in possible degree within at        least 3 minutes. Allowing any insoluble materials settle to the        bottom of the test container.    -   6. Taking a proper aliquot of the dissolved acidified street        sample and placing it into the measuring cell of the device        according to WO2005111586.    -   7. Measuring the SFS of acidified aliquot and detecting specific        spectral pattern of Cocaine. Measuring the intensity of Cocaine        fluorescence at the second phase of two-phase procedure.    -   8. Comparing the intensities of Cocaine fluorescence at the        first phase and second phase of the two-phase procedure provided        that the intensity of Cocaine fluorescence at the first phase is        detected. Higher intensity at the second phase indicates that        Cocaine base is present in the street sample. And on the        contrary, lower or unchanged intensity at the second phase        indicates that Cocaine hydrochloride is present in the street        sample. Absence of Cocaine fluorescence at the both phases        indicates that neither Cocaine base nor Cocaine hydrochloride        are present in the street sample.

The working range for the detection and differentiation is from 5% till100% of cocaine in the sample. According to the procedure it is equal to1 mg-20 mg per 10 ml of water. The real lowest level of cocainedetection in street samples is about 1% or 0.2 mg per 10 ml of water.Intensity of cocaine fluorescence depends on its concentration in thisrange.

The procedure of Cocaine base detection and differentiation from Cocainehydrochloride can be provided automatically by Expert system analyzingthe SFS. Such expert system considers not only the shape and position ofCocaine spectra but their intensities in parallel: appearance of Cocainespectral pattern or increase of its fluorescence intensity afteracidification of the measuring sample is used as the evidence of Cocainebase property of the detected Cocaine.

The data below demonstrate increase of SFS intensity of Cocaine base anddecrease of SFS intensity of Cocaine hydrochloride after acidificationof their solutes in distilled water. Study of time dependence of thesechanges supplements the stated changes.

Table 3 shows application of two-phase analytical procedure fordifferentiation of Cocaine base and cocaine hydrochloride fixed by theapplicant in experimental laboratory samples.

TABLE 3 Fluorescence intensities, a.u. SFS ID First Second Intensitynumber phase phase difference, % Result 8223 653.12 2501.45 +283 Cocainebase 8225 475.58 4603.54 +868 Cocaine base 227 753.54 5809.56 +671Cocaine base 8229 7449.36 6234.73 −16 Cocaine hydrochloride 8231 284.46239.7 −16 Cocaine hydrochloride 8233 4099.25 2056.85 −50 Cocainehydrochloride 8235 5308.69 4927.63 −7 Cocaine hydrochloride 8237 5441.145216.5 −4 Cocaine hydrochloride 8239 774.64 4538.06 +486 Cocaine base8241 769.19 6710.65 +772 Cocaine base 8243 426.75 5053.65 +1084 Cocainebase 8245 6011.37 4887.47 −19 Cocaine hydrochloride 8247 806.53 6293.99+680 Cocaine base 8249 6890.81 5584.47 −19 Cocaine hydrochloride 82516831.84 5908.92 −14 Cocaine hydrochloride

The disclosed embodiment of the invention does not determine its scopeof protection, but shows only one of variants of its realization withinthe scope defined by claims.

1-8. (canceled)
 9. Method for drug detection in a drug sample comprisingthe steps of: a) preparing a liquid sample from a drug sample foranalysis; b) introducing an aliquot of a liquid sample of the drug intoa measuring cell of a Spectral Fluorescence Signatures (SFS) device; c)measuring the SFS of the aliquot liquid sample to obtain a referencevalue of SFS; d) adding acid into the liquid sample; e) introducing theacidified aliquot liquid sample into the measuring cell of the SFSdevice; f) measuring the SFS of the acidified aliquot liquid sample; andg) comparing the reference value and the result of the measurement ofSFS of the acidified aliquot liquid sample, wherein if: i) the SFS ofthe acidified aliquot liquid sample exceeds the reference value Cocainebase is present in the drug sample ii) SFS of the acidified aliquotliquid sample is below the reference value or is equal to the referencevalue, and the reference value is not zero, Cocaine hydrochloride ispresent in the drug sample; and iii) the SFS of the acidified aliquotliquid sample equals the reference value and the reference value iszero, Cocaine is not present in the drug sample.
 10. The methodaccording to claim 9, wherein the liquid sample is prepared bydissolving a dry sample of the drug in purified water.
 11. The methodaccording to claim 10, wherein the purified water is distilled water.12. The method according to claim 9, wherein the amount of acid addedinto the liquid sample is 1 to 2 drops.
 13. The method according toclaim 9, wherein the SFS is not measured for at least 3 minutes afteradding the acid in step d).
 14. The method according to claim 9, whereinthe acid is hydrochloric acid.
 15. The method according to claim 9,wherein the drug sample is a street sample.
 16. The method according toclaim 9, wherein the method is carried out on-site.
 17. The methodaccording to claim 9, wherein the drug sample is suspected to contain anillegal drug.